class GameMap extends  AcGameObject  {
    constructor(playground)  {
        super();    // 调用基类构造函数
        this.playground = playground;
        this.$canvas = $(`<canvas></canvas>`);

        this.ctx = this.$canvas[0].getContext('2d');
        this.ctx.canvas.width = this.playground.width;
        this.ctx.canvas.height = this.playground.height;
        this.playground.$playground.append(this.$canvas);

    }

    start()  {
    }

    update() {
        this.render();
    }

    render()  {
        this.ctx.fillStyle = "rgba(0,0,0,0.2)";
        this.ctx.fillRect(0,0,this.ctx.canvas.width,this.ctx.canvas.height);    //渲染地图(黑色)
    }
     
}